In the interest of economy, it is desirable to limit the number of optical glasses to be produced by a manufacturer. Accordingly, it is desirable to utilize glass compositions which have as many different areas of applicability as possible and which therefore must exhibit a multitude of properties in optimum proportions among themselves. Under ideal circumstances, with respect to a specific position in the n.sub.d /v.sub.d diagram having a "normal " relative particle dispersion (positioned on or near the Abbe line), such glasses possess as many properties having optimal values as is possible. Examples of these properties include good melting properties, crystallization stability, high light transmission, chemical resistance toward the greatest number of influences, low negative interaction with irradiation, easy workability and freedom from hazardous compounds.
Some of these properties lend themselves to being maintained at optimal values in combination, whereas others are difficult to maintain or can be maintained only by using certain special elements. Modern processing and cleaning of the starting materials for glasses, for instance, have the effect of increasingly lowering the solarization resistance of optical glasses made therefrom. It is known that solarization and other irradiation resistance can be increased by introducting small amounts of CeO.sub.2 into the glasses. However, this usually causes considerable deterioration of the transmission curve as a result of a shift of the absorption edge towards longer wavelengths in the UV-range, with the ends of this absorption edge clearly reaching into the range of visible light. Such a result severely limits the applicability of such glasses for optical purposes.